Mechanical steering transmission unit

ABSTRACT

The present invention concerns a mechanical steering transmission unit comprising an input drive shaft and two output driven shafts that can revolve in the same or opposite direction at the same speed.

FIELD OF THE INVENTION

The present application for industrial patent concerns a mechanical transmission unit especially designed for vehicles running on wheels or belts. This unit will allow the vehicle to turn around an imaginary point placed between the couple of belts or wheels without stopping.

Since the mechanism of the invention was developed with the specific aim of solving a typical problem of caterpillars, henceforth the present description will refer to this type of vehicles. However, any vehicle running on four wheels and machines in general can equally benefit from using the mechanism.

BACKGROUND OF THE INVENTION

As it is known, the easiest way to make a caterpillar turn is to brake the belt on the internal side of the curve and block it down completely. The technique is employed to make the vehicle turn on itself using one of the belts as pivot.

It is evident, however, that using this technique it will be impossible to make the caterpillar turn around an imaginary point placed between the lateral course of belts. As it is often the case for some models of highly sophisticated combat tanks, when such a performance is required, the tanks are equipped with special hydraulic transmission units, which employ two hydraulic motors (one for each belt). When needed, the motors start revolving in opposite direction. In this way the centre of curvature of the vehicle falls inside the lateral couple of belts.

It must be stressed, however, that in these cases this performance (that is to make the motors run in the opposite direction) cannot be achieved without having previously stopped the run of the vehicle. This means that it is not possible to make the vehicle turn on itself without previously stopping its straight run.

OBJECT OF THE INVENTION

The aim of the invention is to invent a mechanical transmission unit with two output driven shafts that, when needed, will allow the counter-rotation of the two output shafts. If the aforementioned shafts drive the belts of the caterpillar, a rotation of the caterpillar on itself will correspond to this counter-rotation.

An additional aim of the invention is to develop a mechanical transmission unit with two output driven shafts that will allow the counter-rotation of the two output shafts without stopping them, when needed.

BRIEF DESCRIPTION OF THE DRAWING

In order to avoid any misunderstanding, the description of the transmission unit of the invention will proceed with reference to the enclosed drawing. However, the drawing has the only purpose of illustrating the invention and is not binding in any way. Therefore, FIG. 1 is a cross sectional view which only shows a possible representation of the transmission unit of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the aforementioned figure, the transmission unit of the invention includes a drive shaft (1) that, by means of a couple of bevel gears (2 a and 2 b), drives a driven shaft (3) at whose ends two identical differential gears (5) are mounted from which two driven shafts (6 and 7) can drive the belts or wheels of the vehicle. 

1. A mechanical transmission unit, having an input drive shaft (1) and two output driven shafts (6 and 7) that comprises: a first pair of bevel gears having a first bevel gear (2 a) and a second bevel gear (2 b), the first bevel gear being splined to the drive shaft (1), the second bevel gear (2 b) being splined to a driven shaft (3), that is at right angle to the drive shaft (1); at the ends of the driven shaft (3), two identical differential units (5) are installed, from which the two output driven shafts (6 and 7) originate, a cogwheel (8) that is splined to the drive shaft (1) and gears with a couple of cogwheels (9 and 10) that are identical to the cogwheel (8), each of which is splined to the another pair of driven shafts (11 and 12), which are parallel and whose opposite sides lie near the drive shaft (1), a second pair of bevel gears (13 a and 13 b) and a third pair of bevel gears (14 a and 14 b), which lie near the opposite sides of the first pair of bevel gears (2 a and 2 b) and are used to link differential gears (5) to their the another pair of driven shafts (11 and 12); two identical hydraulic units (15) respectively mounted on the another pair of driven shafts (11 and 12), each of them used to start two antithetical clutches (16 a and 16 b), the former (16 a) controls transmission of motion from the two cogwheels (9 and 10) to their respective driven shafts (11 and 12); whereas the second clutch (16 b) prevents the free rotation of a frame (17) and the another pair of driven shafts (11 and 12), making them revolve in the same direction; it is also being provided that the three pairs of bevel gears (2 a and 2 b; 13 a and 13 b; 14 a and l4 b) are perfectly identical; the first bevel gear of the first pair (2 b) is splined to the driven shaft (3) and lies upside down with reference to the two bevel gears (13 b and 14 b) of the second and third pair.
 2. A-transmission unit according to claim 1, wherein the two output drivin shafts (6 and 7) are parallel and coaxial. 